Desensitization of platelet thromboxane (TX) A2/Prostaglandin (PG)H2 receptors was induced by incubating platelet-rich plasma with the stable PGH2 11 alpha 9 alpha (epoxymethano) prosta 5Z, 13E-dinecoic acid (U46619) (1 M). Iloprost, a stable prostacyclin analog, was included in the incubation to prevent platelet activation.